Photosensitization of biological targets
A photosensitized reaction is a process by which a photochemical or photophysical alteration occurs in one molecular entity as a result of the initial absorption of radiation by another molecular entity called photosensitizer (or simply sensitizer).  more»

Photochemistry of aromatic pterins
Six-substituted aromatic pterins undergo photooxidation in air-equilibrated aqueous solutions under UV-A radiation. Many of these oxidations chemically modify the six-subtituent but do not affect the pterin moiety or at least do so to a smaller extent. The mechanism involved in the photooxidation of these compounds strongly depends on the nature of the substituent at position 6 as well as on the pH (i.e., the photochemistry of the acid and basic forms of the pterin derivatives is different). In the following paragraphs, some examples of photochemistry of pterins relevant form a biomedical point of view are presented. more»

Photochemistry of dihydropterins
Dihydroneopterin (H2Nep), like neopterin (Nep), is synthesized mainly in macrophages when the cellular immune system is activated. Dihydrobiopterin (H2Bip) and its oxidized analogue, biopterin (Bip), accumulate in the skin of patients suffering from vitiligo, a chronic depigmentation disorder in which the protection against UV...more»

Production and quenching of reactive oxygen specieso
Under UV-A excitation (320–400 nm), aromatic pterins (Pt) can generate reactive oxygen species (ROS), as a consequence of both energy- and electrontransfer processes from their triplet excited state. Quantum yields of singlet oxygen (1O2) production depend largely on the nature of the substituents on the pterin moiety, on the oxidation state of the pyrazine ring and on the pH. more»